import java.util.Random;
import java.util.Scanner;

public class YanZH2 {
    public static void main(String[] args) {

        System.out.println("输入验证码位数");
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        System.out.println(ProdurtYan(k));
    }

    public static String ProdurtYan(int k) {
        String p = "";
        String temp = "1234567890qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
        Random r = new Random();
        for (int i = 0; i < k; i++) {
            int t = r.nextInt(temp.length() );
            p += temp.charAt(t);
        }
        return p;
    }
}
